Conventionally carbon-molded products have been used as a conveyor material for conveying hot products (aluminum sections) in the rear equipment of aluminum extrusion press machines (aluminum extrusion process). Though the carbon-molded products are excellent in heat-resistance and long life, the carbon-molded products damages aluminum sections in a form of flaws, dents and spot flaws. Especially, the spot flaws are caused from local rapid cooling of aluminum sections, when, molecular structure changes partially to deteriorate the surface (this phenomenon is called as a black spot). This phenomenon is specific to aluminum alloys (serious especially for 6063 alloy), and the high thermal conductivity of the carbon-molded products (10 to 15 kcal/m.multidot.hr.multidot..degree.C.) causes the rapid cooling.
To cope with this problem, the inventors of the present invention proposed previously a heat-resistant felt for hot products primarily containing carbon fibers and heat-resistant fibers, for example, "a heat-resistant roll for the rear equipment of aluminum extrusion press machines" (Japanese Utility Model No. 1818591) and "cooling table" (Japanese Utility Model No. 1990726). The heat-resistant felts described in these inventions have thermal conductivity of 0.10 to 0.14 kcal/m.multidot.hr.multidot..degree.C., this value is 1/100 or less times that of the above-mentioned carbon-molded products, therefore, these felts do not cause spot flaws.
In the plating line of steel, conventionally conveyor rolls, which are for conveying plated iron plates from a zinc melting vessel (melting point of 420.degree. C.), are wounded with asbestos on the surface, however, because of the environmental health problem of asbestos, recently rolls the outer surface of which roll is covered with a para-aromatic polyamide fiber tube or non-woven fabric rolls have been used. In the manufacturing process of ceramics, especially glass, woven fabrics comprising para-aromatic polyamide fibers are used for conveying glass of about 650.degree. C.
On the other hand, asbestos and mica have been used conventionally in the annealing process of rolling of non-ferrous metals such as aluminum, however, these materials have caused an industrial safety and hygiene problem. In spite of these serious problems, there has been no alternative for these materials.
For a heat-resistant felt for hot products (aluminum sections) discharged from an aluminum extrusion press machine, primarily organic fibers of para-aromatic polyamide fibers or meta-aromatic polyamide fibers alone are used, therefore, the heat-resistance is insufficient at the initial part just after the extrusion press machine where the maximum temperature is 550.degree. C., and the service life of the material is short. To compensate the deficiency in heat resistance, remediations in which water is impregnated in the felt temporarily or the felt is used with carbon-molded products together have been taken, however, these remediations involve troublesome works.
Also in the plating line of iron and the glass manufacturing line para-aromatic polyamide fibers used as a heat-resistant felt is deficient in heat-resistance, therefore, the service life of the felt is short. On the other hand, similarly in the above-mentioned annealing process, the spacer material comprising aromatic polyamide fibers is used at a temperature as high as 350.degree. C. to 550.degree. C., the spacer is thermally decomposed and the service life is short, the short service life being a problem.
It is an object of the present invention in view of the above-mentioned problems in the field of steel, non-ferrous metal and ceramic industries, to provide a heat-resistant felt for hot products excellent in heat-resistance, having long service life, and contributing to the improvement of product quality.
It is another object of the present invention to provide a heat resistant felt for hot products excellent in bonding between fibers, long service life, and dimensional stability. It is a further object of the present invention to provide a heat-resistant felt for hot products excellent in wearing resistance.